|  | 8.2 | Network Security
| 8.2.2 | Data recovery
Data recovery, the second part of network security involves protecting data from loss. There are multiple methods to prevent data from being lost. Usually there is more than one method being used at the same time to protect the data. Three popular data protection methods are Tape Backup of data, fault tolerant disk configurations, and the use of uninterruptible power supplies (UPS) to prevent equipment shutdowns during electrical power outages. We will talk about these three methods in detail in the following paragraphs. Tape backup is the process of duplicating all stored data to magnetic tape. The reason that tape is used is its cost and capacity. Tape cartridges are much less expensive and contain much greater storage capacity than comparable removable hard disks. The drawback that tape has for general usage is that it stores data sequentially, the same way that music is recorded on a tape cassette. This means that just like trying to find a single song on a cassette is difficult to do efficiently, the same is true of trying to find a specific file on a data tape. But since the data for a backup is recorded sequentially and recovered the same way this isn't a problem for this usage. It is important to do a tape backup as completely and quickly as possible, because it can be quite a drain on system resources (network bandwidth and server processor power). To allow for the complete backup to occur most efficiently, different types of backups have been developed. Most of the backup types work with a flag or switch called the Archive bit. The archive bit is stored with a file and turned on whenever that file is created or modified. This flag tells the backup process if the file needs to be backed up or not. If a file is stored to tape during the backup process, normally, the flag is turned off saying that the current file is backed up to tape. Most companies recommend that tapes and backups be stored in some type of fire safe, or they are taken off premises in case of fire or water damage.